1. Field of the Invention
The present invention relates to high efficiency and low carbon monoxide gas burner systems of the type employed with artificial gas logs. More particularly, the present invention relates to a method and apparatus for adding a predetermined amount of metallic salt vapor to the gas to be burned by the gas burner system so that the relatively short invisible blue gas flames appear both longer and colored.
2. Description of the Prior Art
The American National Standards Institute (ANSI) Emission and Safety Standards Z-21.50 (1986) only permits 200 parts per million of carbon monoxide when burning gaseous fuels such as natural gas, manufactured gas and propane. These gasses when burned for high efficiency, high carbon dioxide and low carbon monoxide are known to display a blue color which is typical of the color produced by a gas stove burning natural gas.
Attempts have been made to meet the ANSI pollution standards and to also change the blue gas flame to an orange gas flame which is typical of the flames produced when wood is burned on a grate with an adequate supply of combustion air.
In our U.S. Pat. No. 4,875,464, a gas burner system is shown and described which does meet ANSI pollution standards and does produce gas flames which simulate the size and color of flames produced by wood burning logs. This simulated effect was produced by using hot metal shields to direct the gas flames away from the artificial logs which would act as a heat sink and raise the carbon monoxide to prohibitive levels. Further, the fuel air ratio was set at a near critical level in order to produce the desirable orange colored flames.
In our U.S. Pat. No. 5,000,162, a gas burner system is shown and described which simulates the size and color of glowing embers and which also meets ANSI pollution standards. Heretofore, glowing embers were designed to resemble hot glowing coals or wood charcoal which did not exhibit flames.
It is known that heat-stable metal compounds enhance the combustion of carbonaceous fuels. U.S. Pat. No. 4,992,041 shows and describes ceramic tubes which have a slurry mixture coating of aluminum oxide, soda lime glass and a metallic compound based thereon. The dense slurry which contained a small percentage of metallic compound was formed as a baked coating 1/16th to 1/32nd inch thick on a 1/4 inch tube. The treated ceramic tubes were placed in the secondary reaction zone of the gas flame where the gas temperatures falls in the range between 1200.degree. F. to 1600.degree. F. which is sufficient to affect the release of atoms of metal into the primary reaction zone of the gas flame where they undergo ionizations. The explanation in this patent contends that the ionized atoms when they reach a cooler portion of the flame relax to lower energy levels and emit light characteristic of the light emitting metallic ions. This explanation clearly describes the necessity for driving an ion from the outer orbit of the metallic atom to produce the ionization effect so that when the excited atoms relax to a lower energy level they emitted light characteristic of that metallic ion.
The applicants of the present invention have determined that it is not necessary to ionize the metallic compounds in order to produce a colored light characteristic of the metallic elements. This is not to say that some ionization does not occur in the hot zone but it is possible to drive the metallic elements to a higher energy level so that when they collapse to a lower energy level, they do emit light without ionization.
It would be desirable to provide a method and apparatus for enhancing the length and color of primary gas flames in a gas burner system and at the same time, producing a more brilliant display of glowing embers which can be provided with visible natural colored flames associated with the glowing embers.